The Mayo Clinic successfully destroyed late-stage cancer by using a massive dose of measles vaccine. Stacy Erholtz had run out of treatment options for her blood cancer until she received enough measles vaccine to inoculate 10 million people as part of a medical trial. Now she's in complete remission and the cancer is undetectable in her body. Researchers have been working to test cancer-killing viruses for years, and they've been known to be effective in mice. The Mayo Clinic will launch a larger trial using the measles vaccine no later than September.